One major study found that the percentage of deaths among women ever using oral contraceptives was 12% lower than those that never did.[13,14] Women on birth control pills have an elevated risk of blood clots, but that risk is lower than the risk of developing blood clots during pregnancy and the six weeks after delivering a child (postpartum).
Above you’ll find some of the side effects and and long-term complications of the birth control pill. Perhaps you can review it together with your mother and discuss why she may want you to take it and what other options there may be.
In the current study, we examine the relationship between birth intervals and high school GPA, cognitive ability, and educational attainment, earnings, unemployment status, and welfare receipts. Previous research on the long-term consequences of short birth intervals and high sibling density has generally focused on school test scores, cognitive ability, and schooling transitions, but not on earnings, unemployment, or welfare receipts. As a result, our study reevaluates the relationship between birth spacing and educational and cognitive outcomes, and extends previous research by examining long-term socioeconomic outcomes. Given the volume of research on birth order and family size, surprisingly few studies have examined the long-term consequences of birth intervals (Steelman et al. ). For the most part, research using standard regression techniques and data from the United States has found that shorter intervals and greater sibling density are associated with lower test scores (Powell and Steelman ; Stafford ) as well as a lower probability of making the transition to postsecondary schooling (Powell and Steelman ). Previous research has shown that having more closely spaced siblings is associated with decreased parental investment (Powell and Steelman ). Research on the relationship between birth spacing and cognitive ability has not reached a firm conclusion, with some studies showing that shorter birth intervals and greater sibling density are associated with lower intelligence (Dandes and Dow ; Pfouts ) and other studies finding no relationship (Galbraith ). Short birth intervals may also influence parents’ interactions with their children. Having more closely spaced siblings is negatively associated with the amount of time children spend talking to their mother and father, as well as access to educational materials, even after parental education level and family income are controlled for (Powell and Steelman ).
For the purpose of this study, mothers with children born in 2004–2006 were selected, of whom 43.5 % of those invited consented to participate in the MoBa study . Since several thousand women have participated with more than one pregnancy (>15 %), and as participation in the study was linked to national registers, only unique pairs of mothers and children were eligible. Altogether, data for 40,502 women were successfully linked to the registries. Among these cases, twin and triplet births (1.7 %) and deliveries prior to week 37 and after week 41 of gestation, were excluded (12.9 %), leaving 34,587 cases eligible for the study. Among the eligible cases, we excluded cases where the mother had emigrated or where either the mother or the child had died (1.9 %), children born with severe congenital malformations (2.6 %), and cases for which data on birth weight or gestational age were missing (0.3 %), leaving a sample of 32,938 mothers and children who were residents of Norway in 2010. The study was approved by the Regional Committee for Medical Research Ethics in south-eastern Norway.
Any discussion of the role of birth intervals on long-term outcomes would be incomplete without a consideration of selection processes. Most previous studies on the relationship between birth intervals and longer-term outcomes have largely used standard regression techniques, but factors influencing both the length of birth intervals and long-term cognitive development as well as educational and socioeconomic outcomes may be difficult to adequately adjust for using a standard regression approach. Many prospective parents have a reasonable level of control over when they decide to have a child, which means that birth intervals are endogenous. Two key factors influencing the relationship between birth interval length and long-term child outcomes are parental socioeconomic status (SES) and parental health. It is well established that parental SES is related to offspring socioeconomic attainment (Björklund and Jäntti ), but parental SES is also likely to be related to birth interval length. For example, parents with higher SES might space children more closely to reduce career disruptions (Petterson-Lidbom and Skogman Thoursie ). Unintended pregnancies are also more common at young ages as well as among men and women with lower education and fewer financial resources (Finer and Henshaw ), suggesting that parental SES might be associated with particularly short or particularly long birth intervals, which are more likely to be unintentional. More speculatively, very short or long birth intervals, as well as worse child outcomes, may be partly explained by poor parental planning in regard to both fertility behavior and child raising.
We contend that previous findings are likely to have been driven by omitted variable bias and that individuals with very short birth intervals are negatively selected in ways that are not easily captured by observable measures. Because birth intervals are endogenous, attempting to identify their effect by comparing individuals across different families means that it is extremely difficult to adequately adjust for all the potential factors that predict both the timing of births to a couple as well as the long-term development of their children. In this study, we compare siblings within the same family who were born to the same biological mother and father. By doing so, we implicitly adjust for all factors that are shared and time-invariant, including parental socioeconomic background, the underlying health of the parents, and many dimensions of the home and family environment that would be challenging to measure if it were even practical to do so. These findings provide strong evidence that policies such as the Swedish speed-premium reform do not endanger the long-term development of children. Nevertheless, Sweden has one of the world’s lowest infant mortality rates (WHO ) and highest levels of development. We would therefore advise caution in generalizing our findings about the negligible importance of birth intervals to perinatal outcomes in developed countries with less-extensive welfare states, and especially not to countries that are less economically developed, without further research.
We also conducted additional analyses using different specifications for the birth interval variable in order to make our results more comparable with previous studies on this topic. We used a continuous variable for birth interval length, a quadratic term for birth interval length, and two binary variable specifications indicating whether the birth interval was 19 months or longer or 25 months or longer. Those results are available in Online Resource , Tables and . The results from those additional models are consistent with the conclusions that we draw from the main results presented in this study. Even where there are statistically significant differences, birth intervals have very little substantive impact on long-term educational, cognitive, and socioeconomic outcomes after we adjust for unobserved heterogeneity.
The results for the relationship between the subsequent birth interval and the predicted probability of unemployment show that relative to the reference category, both particularly short and particularly long intervals are associated with an increased risk of unemployment. For subsequent birth intervals of 6–12 months, the predicted probability of unemployment, relative to when the interval is 25–30 months, is .02 higher. The association with the probability of unemployment is slightly lower if the interval is 31–36 months and then roughly increases as the length of the interval increases from 37 months. The results from the within-family comparison again show that after adjusting for within-family factors that remain constant, the length of the subsequent birth interval does not matter for the long-term predicted probability of unemployment for the index person.
The results from Models 3 and 4 (studying the impact of the subsequent interval) are shown in the right panel of Fig. . As with the results shown in the left panel, the between-family analysis shows that a very short interval until the birth of the next sibling in the family is associated with a worse GPA. A preceding birth interval of 6–12 months is associated with a GPA more than 20 points lower than when the interval is 25–30 months. A long subsequent interval is also associated with a worse outcome for the preceding sibling, although this is less pronounced. The relative difference in GPA increases from 0 points to approximately 4 points as the length of the subsequent interval increases from 25 to 30 to >96 months. In the within-family analysis, however, we again see very little difference in the impact of the subsequent birth interval. Some of the differences are statistically significant, but the point estimates never show a difference in the GPA of greater than 2.5 points no matter how long or short the interval until the birth of the subsequent sibling, which is small in substantive terms.
The results of this study show that when residual confounding is reduced to the greatest extent possible by using sibling comparison models, birth intervals do not appear to have any substantial impact on a broad range of mid- and long-term measures of educational, cognitive, and socioeconomic performance. In addition to using a within-family comparison design, this study expands on the previous literature by using a number of different outcome variables at various points in the life course, several of which have not been examined in relation to birth spacing before. Given the consistency of the results when studying six different outcome variables, the degree of precision in the estimates, and the population-based nature of the data, we argue that these results provide compelling evidence that birth intervals, even with very close spacing of less than 12 months, are only trivially related to long-term development in contemporary Sweden. These results are contrary to almost all previous literature that has addressed this topic using standard regression techniques, which has predominantly reported that short birth intervals and high sibling density are detrimental.
However, the results from the fixed-effects analyses—the within-family comparison—tell a different story. Here we see few statistically significant differences by the length of the birth interval, and that the point estimates are far smaller, indicating a difference of no more than 1 or 2 GPA points. Indeed, even where the preceding birth interval was extremely short—less than 12 months—we find no statistically or substantively significant difference in the GPA mark achieved when comparing siblings within the same family. This finding suggests that the results in the between-family analyses are largely driven by differences across families in factors related to both birth timing as well as the educational performance of the children. We consider the results from the sibling comparison model to be a much more accurate representation of the relationship between birth spacing and high school GPA at age 16 because that sibling comparison model allows us to minimize residual confounding that may predict both the length of birth intervals as well as long-term outcomes, such as high school GPA.